A police officer speaks during a press briefing on a high school student suspected of hakcing a total of 3,847 websites since April 2015 at the Seoul Metropolitan Police Agency (SMPA) in central Seoul on June 14, 2016. / Yonhap

By Kim Da-hee

A Korean high school student who allegedly hacked almost 4,000 websites from 87 countries has been arrested.

The student, 16, whose identity was withheld, was charged with hacking a total of 3,847 websites between April 2015 and April this year, police said Tuesday. He is believed to follow international "hacktivist" group Anonymous.

According to the Seoul Metropolitan Police Agency, the student said he learnt hacking from programs accessed via Google. He told police he participated in a hacking operation that Anonymous launched to support Hong Kong's democratic movement in 2014.

Among the 3,847 websites, 141 were Korean, mainly of small and medium enterprises. Police said the student did not damage the sites' private data but displayed a message that read "Website got hacked" on the homepages. The suspect then posted a list of the websites on his social media accounts, they said.

He allegedly committed the crimes to demonstrate his hacking ability. The number of hacked websites could be greater because he allegedly started hacking three years ago, police said.

The student's family had no idea of their son's activities. "My son's academic grade was not bad and he got along well with other students," his parents told police.